To solve the current problems of poor seeding stability and complex maintenance of maize seed-metering devices, a clamp-holding precision maize-seed-metering device is designed. The structure and working principle of the seed-metering device are described, the optimum state of maize seed clamping is analyzed, and the range of each working area of the seed-metering device is determined. The profile and structural parameters of the limit guide plate are designed by analyzing the laws of motion of the seed-picking block. A mechanical model of maize seeds under the critical state in each working area of the seed-metering device is established. The influence of the seed-metering device's rotational speed and the clamping force of the seed-picking block on the seeding performance are analyzed. A physical prototype of the seed-metering device was made for bench tests and field verification tests. The qualified, multiple seeding, and missed seeding rates of the designed seed-metering device were 94.21%, 3.52%, and 2.27%, respectively, meeting the agronomic requirements of maize sowing. The study provides theoretical guidance for designing and optimizing precision maize-seed-metering devices.

To improve the accuracy of the parameters used in the discrete element simulation test, this study calibrated the simulation parameters of cotton seeds by combining a physical test and simulation test. Based on the intrinsic parameters used for the physical test of cotton seed, according to the freefall collision method, inclined plane sliding method, and inclined plane rolling method, the contact parameters of cotton seeds and cotton seeds, stainless steel, and nylon were measured, respectively. The physical test of the accumulation angle and angle of repose of the cotton seeds was conducted. It was obtained to process the image of the seed pile with Matrix Laboratory software. The Plackett–Burman test was used to screen the significance of the simulation parameters. The optimal value range of the significant parameters was determined according to the steepest climbing test. The second-order regression model of the significant parameters, the stacking-angle error, and the angle-of-repose error were obtained according to the Box–Behnken design test. Taking the minimum stacking-angle error and angle-of-repose error as the optimization target values, the following optimal parameter combination was obtained: the interspecies collision recovery coefficient was 0.413, the interspecies static friction coefficient was 0.695, and the interspecies rolling friction coefficient was 0.214. Three repetitive simulation experiments were conducted to prove the reliability of the calibration results. The research results can be used for discrete element simulation experiments for cotton precision seed metering.

To realize the real-time monitoring of the cotton precision seeding operation process and improve the intelligence level of cotton precision planters, based on automatic color matching detection technology and visualization technology, this study designs a monitoring system for the sowing quality of cotton precision planters. The monitoring system is based on the double-silo turntable type cotton vertical disc hole seed metering device as the research carrier, and is composed of a missed seeding monitoring module and a visualization module. Among them, the missed seeding monitoring module includes an incremental rotary encoder, color code electric eye color fiber optic sensor, color code sensor amplifier, etc.; the visualization module includes data acquisition module, industrial computer, and so on. The missing seeding monitoring module is installed on the seed spacer of the cotton precision seed metering device. It uses Labview software for graphical programming and is equipped with a multi-functional industrial computer. It realizes the monitoring of parameters such as the number of sowings, the number of missed sowings, the speed of the hole seeder, the forward speed of the machine, and the sowing area. The results of the bench test and field test of the sowing monitoring system showed that the accuracy rate of the system’s broadcast monitoring was over 93%, and the accuracy rate of missed broadcast monitoring was over 91%. The system solved the technical problem that cotton film-laying and sowing were not easy to detect. It could accurately detect the quality of cotton sowing in real time and meet the actual requirements of sowing monitoring.

With the extensive use of plastic film mulching in planting, the amount of residual plastic film in soil has been increasing, causing soil and water pollution, harming crop growth, and reducing agricultural product quality and yield. In response to this issue, this study proposes a roll-type residual film recovery mechanism using the tillage layer method. The structure and operation principles of this system are discussed, and a detailed analysis of its key components and working process is provided. The lifting cutter operates at a speed of 22.37 rad/s, the pick-up drum at 4.58 rad/s, the roll forward rotation picks up the film at 13.74 rad/s, and the roll reverse film rotation unloads the film at 17.57 rad/s, with the unloading wheel rotating at a speed of 4.5 rad/s. ADAMS (software of automatic dynamic analysis of mechanical systems) Version No.2019 is used for modeling and analysis, and the displacement and velocity change patterns of MARKER_499, MARKER_500, and MARKER_505, which are marked points of the spring-tooth tips and are found to be the same. The maximum resultant displacement of MARKER_499 and MARKER_500 is 22.146 mm when picking up plastic film and 17.047 mm when unloading plastic film. Meanwhile, the maximum resultant displacement of MARKER_500 and MARKER_505 is 231.715 mm in the film-picking area and 234.028 mm in the film-unloading area. After analyzing the velocity of MARKER_499 during picking and unloading of the film, it was determined that the absolute velocity for the picking direction was 79,809.407 mm/s, and for the unloading direction it was 10,2266.168 mm/s. Bench tests show a tillage gathering rate of 71.6% and a surface gathering rate of 83.4%, meeting the performance requirements of the roller-type residual film recovery mechanism. These findings provide a theoretical basis for the design of the structure and operational parameters for the roll-type residual film recovery mechanism using the tillage layer method.

In order to further improve the seeding performance of the maize seed-metering device, a pressure-holding precision seed-metering device for maize was designed. The seed-metering device is made up of several seed rowing modules, which effectively solves the problems of inconvenient disassembly and complex maintenance of the current maize seed-metering device. The working principle of the device was introduced, and the mechanical and kinematic analysis of the maize seeds during the seeding operation was carried out. The orthogonal test was carried out with the installation diameter of seed-metering device's guide plate, torsion spring's wire diameter and seed-metering device's rotational speed as the test factors, the single-seeding rate, missed-seeding rate and multiple-seeding rate as the indexes, and the relationship between different test factors on the performance of seed-metering device was obtained. By optimizing the model, the best performance of the seed-metering device was obtained when the installation diameter of the guide plate was 92.32 mm, the wire diameter of the torsion spring was 1.59 mm, and the rotational speed of the seed-metering device was 0.41 r/s. At this time, the single-seed rate was 93.08%, the missed-seeding rate was 3%, and the multiple-seeding rate was 3.9%, which met the requirements of the industry standard.